Synthetic oil is definitely superior in high heat, high stress situations. There are two ways of looking at it with boats: 1) they have unlimited access to cool water for engine cooling which keeps oil temps down, but 2) they're consistently running high rpm's and heavy loads.

Personally I'd rather be overkill with my engine oil. Change it frequently and use the best quality product you can. I've always run synthetics in my boats. I also tend to go to a 10-40 weight. Something a bit heavier since boats rarely run in cold temperatures.

Nu Bu is both right and wrong. Conventional oils work great and do not tend to break down in a marine engine due to the relatively cool temps they run at. However, synthetic oils prevent sludge build up much better than any conventional. Sludge does not need high temps to form, just age since all conventional oils have a limited amount of wax in them (from the refining process). Synthetics do not have the wax leftovers, so they form less sludge over time. From my experience the best synthetic oils are Penzoil Platinum or NAPA house brand - for the price. Buy on sale for about $20 an oil change (5-quarts). Don't stress on weight with synthetics, the exact same oil can be classified as a multitude of weights as the tend to perform well over a broad spectrum.

NAPA Gold oil filters meet all marine specs without the high cost of dealer supplied. The difference is case burst pressure.

If your impeller is working, the engine oil will be kept cool, but those impellers seem to fail more than a water pump/radiator in a car and like to have the added protection of a synthetic. The difference in price between conventional and synthetic is less than the price of 5 gals of gas.

Beyond the fact that the oil is chnaged so frequently can you please expand on that Nu Bu?

Sure. The benefit of better peformance under higher pressure and higher temperature operation doesn't apply because they don't exist on our kinds of boats. Can't take advantage of the longer drain intervals unless you want to void your engine warranty. Better fuel economy, I don't think I need to address that one.

I'm not saying synthetics aren't good oils, I'm saying they are a waste of money. If the manufacturer of the motor that was in my boat required synthetic I'd use it, but that's the only reason.

The good question is why wouldn't you run synthetic oil... just plain and simple its better... the only downside is it cost more, and lets be honest guys does an extra 20 bucks a couple times a year really matter to most of you guys with 50k-100k boat?

can anybody in the know answer this question? I have heard that one downside of synthetic oil is it does not stick ( for the lack of better term ) to the engine metals as well as conv. oils. Since boats sits longer between use, compared to cars, you have more engine wear on start up when using syn. oils.

+1 synthetics are a waste of money IMO. I run dino oil in all my vehicles, and usually run them into the ground before I replace them. Never had an oil related failure. Frequency of oil changes is much more important than the type of oil.

+1 synthetics are a waste of money IMO. I run dino oil in all my vehicles, and usually run them into the ground before I replace them. Never had an oil related failure. Frequency of oil changes is much more important than the type of oil.

Oil threads always turn into wars.

Yup people sure do get spirited when they hear they've been waisting their money.

S Dub, synthetics are superior for long standing periods rather than what you had heard. When an engine blows on a race track it takes much longer to clean up a synthetic than a conventional because they adhere to the surface better. They are more stable over time as the oxidation rate is less. Most synthetics flow faster when cold so on initial start up they provide lubrication to the valve train sooner than standard oils.
The other benefit in a boat is a slight reduction in drag so you have a touch more power.
NuBu is right that a cool engine operating environment does not give all the benefits you might expect in another vehicle.
If you burn or leak oil you do not want synthetic. It just adds to your expense as it burns faster and leaks quicker.

I use synthetic in my vehicles and boat. A my old, and I mean old, I/O runs conventional.

Totally agree with Art. Synthetics are a superior chemistry and perform better in every regard. Folks can argue about whether or not a marine engine environment warrants the superior chemistry or not. I can appreciate both arguements honestly. But, for me, I use synthetic because it is better in every sense (unless you burn oil or have a leak, as Art mentions). I like to take good care of my equipment in hopes that it will take good care of me :-)

Anybody that doesn't think marine life is hard on oils hasn't ever ridden in a loaded boat. Our boat gets full throttle shots for 30 seconds at a time every time we pull a rider up. It then sits at 4k rpm's at ride speed. Cruising unloaded results in 4200 rpms at 28mph. Tell me that's not hard on a 400 hp, 6.0 litre pushrod motor. For the extra few bucks I'll take synthetic.

That said, I agree that oil change frequency is more important than oil type.

actually, i think you have that backwards. synthetics burn off slower. And I believe that the temperature of your engine is measuring the water temperature as it flows past the thermostat it's not actually indicating the oil temperature which of course is a lot higher than your 160/180 that your boat gauge is indicating.

actually, i think you have that backwards. synthetics burn off slower. And I believe that the temperature of your engine is measuring the water temperature as it flows past the thermostat it's not actually indicating the oil temperature which of course is a lot higher than your 160/180 that your boat gauge is indicating.

I don't think anyone said an engine in a boat doesn't work hard, but it's heat that damages and breaks oil down and a boat simply does not run hot in comparrison to a car. Running synthetic in a boat sure as hell won't hurt anything, but most marine engine manufacturers say not to run it until after 100 hrs of use.

It would be interesting to get some oil temperature readings. You never know.

One of my track cars actually ran cooler oil and coolant temperatures on the track than on the street. The only explanation I could come up with was the continuous airflow and high rpm's kept things circulating. That and efficient coolers (coolant and oil). I had another that worked the other way. Oil temp went to the moon on the track.

On a boat with continuous high rpm's and unlimited cooling it would be interesting to see what happens.

Synthetic oil offers the same benefits in boats as it does in all other engines. Also, lots of boaters like the remote filter kits offered by Amsoil because they make changing filters much easier in the cramped engine compartments. Check it out here.

It's also funny to hear guys say it doesn't matter when you see teams like Bob Teague just win the superboat GP in Sarasota and he's sponsored by Amsoil. Once you have thousands of dollars in a boat engine why rely on oil that's a dollar a quart and the same thing my grandpa used just after he retired the horses.

Sponsorship = free product. Of coarse you run it when someone else is footing the bill. Best friend has 20k in his flat bottom engine. All aluminum, Brodix heads, blower, all the good stuff and pro built by one of the renound builders in the area. Recommended oil by builder = Castrol 50w racing, non synthetic. Oil type is such a small part of the overall engine building picture.

Synthetic oil offers the same benefits in boats as it does in all other engines. Also, lots of boaters like the remote filter kits offered by Amsoil because they make changing filters much easier in the cramped engine compartments. Check it out here.

It's also funny to hear guys say it doesn't matter when you see teams like Bob Teague just win the superboat GP in Sarasota and he's sponsored by Amsoil. Once you have thousands of dollars in a boat engine why rely on oil that's a dollar a quart and the same thing my grandpa used just after he retired the horses.

The motors are high HP that are torqued down. The description that used to be on mercruisers site for my blackscorpion was something along the lines of it being just like their yada yada race motor but set up to produce more torque, something like that. Not all the motors are, but some of them are pretty performance oriented.

Lets just get diesels in these monsters. Torque is what we need anyways
and idk about you guys, but I <3 Torque

I use synthetic oil in my outboard because I'm lazy and I use the hell out of my boats. I average 200 hours a year on just the little boat we use for boarding and inshore fishing. This boat runs a 2005 Suzuki 4 stroke outboard. After 100 hours run-in I switched to Amsoil in the gear case and engine. I have run the valve clearances every 200 hours and they have not budged one iota. The thing runs perfect. I change the oils once a year at around 200 -250 hours.

So the moral of the story is I pay $8 a quart so I only have to change the oil once a year.

Have you read indmars recommendations for boats operating on small lakes? Because of fuel dilution they recommend 25 hour oil changes if you don't regularly run your boat at or above 4k for fifteen minutes at a time. They also mention excessive idling as a cause to this. These are reasons why you should be running a diesel oil and personally, I think a synthetic with a lot of additives.

Synthetic oil offers the same benefits in boats as it does in all other engines. Also, lots of boaters like the remote filter kits offered by Amsoil because they make changing filters much easier in the cramped engine compartments. Check it out here.

It's also funny to hear guys say it doesn't matter when you see teams like Bob Teague just win the superboat GP in Sarasota and he's sponsored by Amsoil. Once you have thousands of dollars in a boat engine why rely on oil that's a dollar a quart and the same thing my grandpa used just after he retired the horses.

^^Welcome to Wakeworld. Interesting choice for your first post. You need to work on sounding less condescending, and less obvious with your motives if you want to sell more Amsoil. ^^

Oil war aside, I do have to question the OP's choice of weights. 5W30 is really thin - AFAIK the only real advantage is fleet fuel economy improvements. The marine motors I've been around all recommend 15W50 or 20W50.

I would check with your dealer. I purchased my boat used last fall so I checked with the dealer to see what they recommend and for my year/model etc. they specifically said not to use synthetic just a good heavy weight oil.

I would check with your dealer. I purchased my boat used last fall so I checked with the dealer to see what they recommend and for my year/model etc. they specifically said not to use synthetic just a good heavy weight oil.

Or you can check with your engine manufacturer...indmar says it's fine after the initial 100hr break-in period.

^^^ Sorry man. No way ANY type of oil is staying in my boat for 100hrs. Plain aint gonna happen. Glad it works for you. And no way any type of oil is staying in my gas or diesel truck or any other vehicle for more that 3k. And I've never had a oil related failure either. Thats great you guys get to ride so much. 50hrs is what I tell people, but I'ts so quick and easy for me 25hrs dont bother me. Get this, I do V-drive and tranny every other oil change. See I don't have the luxury of a new boat every other year. My stuff has to last until I hit the lottery! LOL

As I sit here I cant help but do some math Guido. So you guys do approximately 6 hrs a day, 4 days a week. Thats 24 hrs a week. So in a heavily loaded big block Star, I'm guessing what about 8 gph if not more? So thats 192 gallons per week times say $3.25 a gallon for premium which is roughly $624 per week or $2,496 a month in fuel. DAMN!

It seems that everyone thinks that the only advantage to synthetics is longer change intervals (which is not recommended in a boat). This is just not true. Synthetics have better lubricity properties than conventional oil right from the start.

^^^ For the most part the benifits from synthetic are realized in the longer intervals because it doesent break down like conventional oil. But by the time conventional oil is breaking down, it's time to come out because of the alkalyds, acids, carbons and other contaminants that wind up suspended and mixed in with the oil. These by-products are a result of combustion and dont get filtered out. That is why no type of oil stays in any engine of mine for long intervals and never will. There is no real benifit for me to justify the extra dollars spent over the years. Synthetic is mostly hype. It's all in the change intervals. Carry on.

^^^ For the most part the benifits from synthetic are realized in the longer intervals because it doesent break down like conventional oil. But by the time conventional oil is breaking down, it's time to come out because of the alkalyds, acids, carbons and other contaminants that wind up suspended and mixed in with the oil. These by-products are a result of combustion and dont get filtered out. That is why no type of oil stays in any engine of mine for long intervals and never will. There is no real benifit for me to justify the extra dollars spent over the years. Synthetic is mostly hype. It's all in the change intervals. Carry on.

Like I said, synthetics are superior in lubricity even when just put in. I will stick with my Amsoil. It just makes me feel better knowing I am using a superior oil.

Well I dont want to speculate on thier behalf. I'm just saying an established, reputable engine building company like PCM, I'm sure has done thier homework.

In no way bashing on PCM, but I might disagree here. Id like to see a legitamate reason as to why PCM would go against sythetic oil, its basically a car engine, most auto manufacturers suggest using regular oil im pretty sure, ill look at my ford manual, but im sure it says to use motorcraft stuff which is not synthetic. We still use sythetic in car engines.

Where did you guys see that PCM does not want Synthetics in their engines? That is wrong

Here is the exact text from the 2010 Operation Manual.

Synthetic engine oils may be used in PCM Marine
Engines. Synthetic oils must meet the Engine Oil
Requirements for Classiﬁcation and Viscosity listed
below. The use of synthetic oil does not permit the
extension of oil change intervals. operation or 120 days, whichever occurs ﬁrst

Synthetic engine oils are not recommended for use
in PCM Engines. Synthetics may offer advantages
in cold temperature pumpability and high temperature
oxidation-resistance. However, synthetic oils have not
proven to provide operational or economic beneﬁts
over conventional petroleum-based oils in PCM Engines.
Their use does not permit the extension of oil change
intervals.
or 120 days, whichever occurs ﬁ rst
sion Classiﬁ cation and

Well, is the verdict using synthetics is only going to hurt your wallet and not your boat (unless the boat is a much older model)?

I think this argument is ridiculous, because I am almost willing to bet that if pro-synthetic (myself included, in the boat anyway) users posted the particular brand they used, there would ensue an argument about which synthetic is the best. There would be a similar argument about particular conventional oil brands.

I think it's funny. Even the people who are against synthetic's because of the cost, say that synthetic's are better. It might be overkill, but I like overkill. And it's not even that expensive. Walmart has 15w-50 Mobil 1 in 5 quart cans for $21.

Well I dont want to speculate on thier behalf. I'm just saying an established, reputable engine building company like PCM, I'm sure has done thier homework.

Yeah- They've done their homework. If you are running synthetics, your engine is going to last longer!!! They would rather have your engine wear out so they can sell you parts, or a new engine when it's toast..... Come on... Why do you think the manufacturers don't want you to run synthetics?? If they sold you a product that lasted forever, they wouldn't have a chance to sell you anything ever again!!

Sorry, but the cost difference is about $30-$40 per oil change, a couple times a year??? Seams pretty minimal compared to the boat, gas, gear, etc.....

When something seems not quite right (like a manufacturer recommending an inferior product), just follow the money....

Yeah- They've done their homework. If you are running synthetics, your engine is going to last longer!!! They would rather have your engine wear out so they can sell you parts, or a new engine when it's toast..... Come on... Why do you think the manufacturers don't want you to run synthetics?? If they sold you a product that lasted forever, they wouldn't have a chance to sell you anything ever again!!

Sorry, but the cost difference is about $30-$40 per oil change, a couple times a year??? Seams pretty minimal compared to the boat, gas, gear, etc.....

When something seems not quite right (like a manufacturer recommending an inferior product), just follow the money....

idk if thats there ultimate goal, cause how often do you hear about major work being done to a motor in a boat, re-boaring or sleeving cylinders? Most of what goes wrong on our motors are simple little fixes.

I really think they dont recommend it because they havent put in the time in R&D. They know dino oil will work fine, so why spend the extra time/money to test synthetics? They dont explicitly say not to use synthetics do they?
Ford doesnt recommend you use motorcraft oil (which isnt synthetic) so that the motor wears down and they can sell you parts sooner....

I use full synthetic in my boat. its an automotive engine adapted for marine use, which means its tuned differently and has different exhaust/intake, those things arent going to change oil performance. How could its lubricity be changed by any of those factors? And it may be overkill, but would you rather have overkill or underkill?

Yeah- They've done their homework. If you are running synthetics, your engine is going to last longer!!! They would rather have your engine wear out so they can sell you parts, or a new engine when it's toast..... Come on... Why do you think the manufacturers don't want you to run synthetics?? If they sold you a product that lasted forever, they wouldn't have a chance to sell you anything ever again!!

Sorry, but the cost difference is about $30-$40 per oil change, a couple times a year??? Seams pretty minimal compared to the boat, gas, gear, etc.....

When something seems not quite right (like a manufacturer recommending an inferior product), just follow the money....

No. I don't really remember seeing that in any commercials or anything like that..... I use Amsoil is everything I own, and I don't know if I've ever seen an Amsoil commercial.....

My info comes from a friend of a friend (yeah, a bit disconnected, I know). He's a lubrication engineer. He does the actual ball bearing wear tests, and tries to formulate better products and additives. He said that the full synthetic oils are much, much better than conventional- but that the conventional is "good enough". So, take that as you will..... Conventional is good enough, but synthetic is better. If the oil is more slippery, your engine is going to last longer..... bearings will last longer, and rings will seal longer.... Granted, there are other factors that may lead to a premature failure- but if the parts that wear out have better lubrication, they're going to wear longer....

No. I don't really remember seeing that in any commercials or anything like that..... I use Amsoil is everything I own, and I don't know if I've ever seen an Amsoil commercial.....

My info comes from a friend of a friend (yeah, a bit disconnected, I know). He's a lubrication engineer. He does the actual ball bearing wear tests, and tries to formulate better products and additives. He said that the full synthetic oils are much, much better than conventional- but that the conventional is "good enough". So, take that as you will..... Conventional is good enough, but synthetic is better. If the oil is more slippery, your engine is going to last longer..... bearings will last longer, and rings will seal longer.... Granted, there are other factors that may lead to a premature failure- but if the parts that wear out have better lubrication, they're going to wear longer....

For the small price difference, I'll take the better protection.

hahaha dude does that guy work for KY!? that would be awesome. Im not bagging on him, but thats freakin hilarious if he did. did he major in chemical engineering and his job title is lubrication engineer?

hahaha dude does that guy work for KY!? that would be awesome. Im not bagging on him, but thats freakin hilarious if he did. did he major in chemical engineering and his job title is lubrication engineer?

I'm not sure his "title" .... Sorry if my title was funny.... I just emailed our mutual friend to try to find out who it was he worked for. I honestly can't remember if it was some type of independent lab, or one of the big companies....

I'm not sure his "title" .... Sorry if my title was funny.... I just emailed our mutual friend to try to find out who it was he worked for. I honestly can't remember if it was some type of independent lab, or one of the big companies....

haha nah its just my maturity showing get it....KY? ya know "lube" haha. im just giving you a hard time man!!